Growth of Superconducting Oxide Crystals

Progress in the elucidation of the intrinsic materials parameters and underlying physics of the new high temperature superconductors has depended on the study of single crystal samples. The growth of bulk single crystals of these perovskite-related phases, complex compounds with large unit cells, ternary or quaternary constituents, and, in many cases, variable oxygen stoichiometries, is a challenging task. Platelets of Ba sub 2 YCu sub 3 O sub 7 with surface areas approaching 1 cm sup 2 are obtained from CuO-rich eutectic melts. The oxygen stoichiometry of the as-grown crystals can be adjusted by controlling the annealing temperature and oxygen partial pressure to vary properties of the crystals including T sub c 'S and far-infared reflectivity. Systematic alterations in crystal properties can also be achieved by deliberate introduction of impurities.